How to find the father of an illegitimate child

13-year-old’s father confronts teacher who sexually abused his son
13-year-old’s father confronts teacher who sexually abused his son

In most families, sooner or later you will encounter a child born to an unwed mother. Finding the fathers of these ‘illegitimate’ children can be difficult, but not necessarily impossible.

I’ve researched dozens of these cases, both in my own tree and for clients. In four cases, I have been able to prove who the father was. In two other cases, I have developed good theories which I hope to prove through DNA. In the majority of cases, I ended up with a list of possible fathers, but no clear candidates. With the growing popularity of DNA testing and advances in tools for exploring DNA matches, it may be possible to solve these cases in the future.

While working these cases, I developed some strategies that may help you with your own cases too. I will use anonymized examples from my own research to illustrate how you can find out who the father of the illegitimate child was.

Strategy 1: Examine records from around the birth

Many unmarried women tried to hide their pregnancies so a pregnancy may have gone unnoticed in the community until the child was born. At that point, there are several possible records that may have been created:

  • A birth record may reveal the father. Notes in the margin may show if a man later acknowledged the child as his (which does not mean he was the biological father but he may have been).
  • A baptismal record may name the father. In the Netherlands, we often don’t look for baptismal records after the introduction of the civil registration in 1811, but they can reveal important information since churches often took a firmer stance against children born out of wedlock than the civil authorities.
  • Church council minutes may record how the mother was censored and perhaps contain interviews with the midwife to see if the mother uttered the name of the father during labor. The church council tried to make the mothers confess the name of the father so he could be admonished too, or censored for adultery if that was the case.

How to find the father of an illegitimate child

Birth record of a child who was subsequently legitimized when her mother married (note in the margin)

Even if one of these records states the name of the father, this does not prove his paternity as the mother could have been lying or may not have been certain about the identity of the biological father herself. Like all evidence, it must be analyzed for reliability and compared to other records.

In one case, I researched a woman who had eight illegitimate children. The informant on all the birth records was the same man. One of the children was born in another town. In that birth record, the man was not only listed as the informant, but also as the father. According to official instructions, clerks were not supposed to record the names of fathers of illegitimate children, but the clerk in the second town ignored that instruction and wrote it down anyway. Further research showed that they were living together the whole time so it is very likely that he was the father of the other children too.

Strategy 2: Find out where the mother was around the time of conception

If the child lived, the pregnancy was probably full-term or close to full-term. This means conception probably took place around nine months before the birth, but to be on the safe side I recommend using a slightly wider range of seven to ten months. Try to find out where the mother was living and working around the time of conception. Possible records to consult:

  • Population registers (after 1850) and census records
  • Church membership records, which show when the mother came to live in the town
  • Newspapers

Strategy 3: Research the men in the mother’s life

Try to find out who the men in the mother’s life were, especially around the time of conception. Who was she living with? Who was she working for? Who were her neighbors? In one case, I discovered in the population register that the man who later married the mother was already living with her before the child was born.

As sad is it is to say, do not automatically exclude family members as potential fathers. I once found a court case where a stepfather was found guilty of sexual assault of a minor, his 16-year-old stepdaughter. A year after he got out of jail, she had an illegitimate child while still living at home. The stepfather was the informant on the child’s birth certificate. This does not prove that he was the father but the circumstances make him a likely candidate. I recommend that any adult (or at least: teenage) man in the mother’s life be treated as a candidate to be the father, regardless of whether he was related to the mother or not.

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Records that can reveal which men were in the mother’s life are:

  • Population registers (after 1850) and census records which show whole households and show the neighbors
  • Birth, marriage and death records of the civil registration
  • Baptismal, marriage and burial records of churches
  • Tax records which show the neighbors

For each of the men, try to find out where they were in the period seven to ten months before the birth of the baby to see if you can rule any of them out.

Strategy 4: Get to know the mother

To speculate about the situations in which the mother may have gotten pregnant, it is important to try and get to know her. What was she doing for a living? How rich were her parents? How old was she when she got pregnant? What were her circumstances? A teenage servant girl who worked on a farm would find herself in different situations than a 40-year-old widow of an innkeeper.

For one of my ancestors who had two children out of wedlock, I investigated if she might have been a prostitute. To maximize your chances of finding the father, it is important not to make any assumptions or judgments and keep an open mind to all possibilities.

Strategy 5: Analyze the baby’s name

An important clue that the mother may have left you could be the baby’s name. Sometimes, unmarried women named the baby after the father, perhaps in kind remembrance or maybe in an attempt to persuade him to take responsibility. Dutch children were usually named after family members, so if the child has a name that does not occur in the mother’s family, that can be a clue to the father’s identity.

For this strategy, it is important that you know all the people in the mother’s family: parents, siblings, aunts, uncles and any close step-relati0ns. If the child is named after one of the maternal grandparents, that explains the name of the child and it does not help to find the father. But if the mother chose a different name, it may well point to the father’s identity. This is particularly interesting if the name is unusual and there was a man in the mother’s life with that name.

Mother with baby and child

Mother shortly after giving birth. Unknown photographer, circa 1885. Credits: Rijksmuseum

Strategy 6: Understand the community

To understand how your female relative might have found herself pregnant, it is important to understand the community she lived in. A few questions you could ask are:

  • Were there many women who had illegitimate children?
  • What ages were most women who got pregnant out of wedlock?
  • Were there many couples who had their first child within nine months of the marriage? If so, premarital sex may have been common. In some regions and social groups, couples waited until the bride was pregnant to get married, to ensure that she was fertile. It is easy to see how a girl could be abandoned before the marriage.
  • Were there many migrants in the community? The ‘suspect pool’ in a bustling merchant town would look very different from that in a sleeping village in the middle of nowhere.
  • Was prostitution legal and common? During large parts of the history of the Netherlands, prostitution was legal (it is today). Pregnancy was an occupational hazard for these women.

Answering these questions can be difficult. Perhaps someone is doing a one-place-study in the town where she was living in. Genealogists who do one-place-studies often have a good understanding of local traditions. If not, local genealogical societies might be able to help.

Strategy 7: Find out what was going on

Sometimes local events influenced how people behaved, which could result in pregnancy. A good example is the wave of ‘liberation children’ left behind by allied soldiers in World War II.

In order to understand if local events played a role in the conception, find out what was going on in the town about seven to ten months before the birth. Things to look out for are:

  • Presence of soldiers, for example an invading army, liberating army, soldiers quartered in houses.
  • Presence of a carnival or traveling show.
  • Was there an annual market or fair? This brought in people from several surrounding villages and also would have come with festivities and drinking that may have lowered inhibitions. The mother may have brought a local boy to the fair with her so just because there was an annual fair does not mean that the father had to come from somewhere else.
  • Was it harvest time? Often, when the harvest was over, the workers celebrated. The father may have been a fellow farm hand.
  • Criminal behavior, like rapists, in the neighborhood.
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Local newspapers are a great source of information for these types of events. Many Dutch newspapers can be found at Alternatively, annual reports to the government by the municipality or police reports can shed light on what was going on. Magazines or books by local historical societies can also be a great source of information.

Painting of a market with two drunk men

Two drunks at Amsterdam market. Peter Paul Joseph Noël, 1821. Credits: Rijksmuseum

Strategy 8: Follow the money

In rare cases, mothers sued the father for child support, for loss of virginity or for breach of promise. These cases can be found in court records.

I once found a 17th century case file before the Court of Gelderland where an unmarried mother sued the father of her child. She details how he seduced her in the garden of the minister for whom she was working as a servant. He did not deny this but brought in a witness who testified that he had also had carnal knowledge of her, casting doubt on her moral character and the paternity of the child. She denied this and produced evidence that the second witness was a first cousin to the father and thus not unbiased. Unfortunately, the verdict has not been preserved but I would say the preponderance of evidence was in her favor. While not all court cases are this informative, they can be helpful to create a list of candidates.

In another court case, a poor servant girl sued the rich farmer she was working for, but the rich farmer said she was involved with the hired hand instead. Without additional evidence it is hard to say who spoke the truth: it is understandable that the married farmer would like to shift blame if he was the father, but it is also possible that the mother chose a richer target to sue than a poor hand who could not provide for her or her child.

It is also worth investigating if the material wealth of the mother improved after the birth, indicating that perhaps she was paid off. I’ve heard several family stories where a poor servant girl is paid off by the rich farmer, who found her a husband to marry and gave them some land or a house. Circumstances that suddenly increase should set off alarm bells that perhaps the biological father may have been rich.

Strategy 9: Research from cradle to grave

If nothing else works, research the entire lives of the mother, child and any potential fathers that you have identified.

Did the potential father ever interact with the mother or the child at a later point? Sometimes fathers remained involved in the children’s lives even if they would or could not legally recognize them. Perhaps the candidate father witnessed records involving the child, or acted as godfather to his (grand)children. I have never seen a case in Dutch records where a father mentions an illegitimate child in his will, but that is easy to check too. Don’t dismiss their earlier lives either. The candidate father may have been named as the father of other illegitimate children, which gives you an idea about his character.

There could also have been an impediment that prevented the father from acknowledging the child at the time of the birth, for example if he was married and was unable to get a divorce. But if he later finds himself a widower, it is possible that he would then marry the mother. He would not be able to legitimize the child, as it was born when he was married, so the fact that he does not acknowledge the child does not say anything about him being the biological father. For any man that the mother marries, it is worthwhile to find out if he was in the picture around the time of conception.

Strategy 10: DNA testing

Anybody who wanted to prove the paternity of a child today would turn to DNA. But DNA can even help solve older cases. There are several options.

If you have a candidate for the father, you can test specific people to see if they match. There are two options:

  • Y-DNA testing. Y-DNA inherits from father to son so you can use this kind of test if the illegitimate child is male and has a strict male-line living descendant. You should then find a strict male-line living descendant of the potential father (or his brother or paternal cousin, as long as they share a ancestor in the strict-male line). If both men agree to test, you can compare their results. If the results match, this is good evidence that your theory is correct. If the results do not match, your theory may be flawed, or there may have been a non-paternal event somewhere down the lines in either of the two men that tested. Y-DNA testing will not help you to determine which of two brothers or paternal cousins is the father but it can help narrow the suspect pool.
  • Autosomal testing. Autosomes are the non-sex chromosomes that get recombined each generation and half of them gets transmitted to a child. After about four generations, there are no guarantees that two descendants will share DNA so this type of test is especially useful if the illegitimate child was just a couple of generations ago. To use autosomal DNA testing to prove the identity of the father, you need one living descendant of the illegitimate child and one living relative of the potential father, who is not also related to the mother. If they share autosomal DNA this is evidence that it is the correct father.
    In these cases, I always research the pedigrees of both test subjects and compare them carefully so I am sure that there aren’t any other shared ancestors that could have contributed to any shared DNA. I want to make sure that any DNA that they share must have come from the alleged father.
    With autosomal testing you want to test the oldest generations that you can, as 50% of the autosomal DNA is lost which each generation.
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If you do not have a candidate for the father, you want to test descendants to see which people they match. All major DNA testing companies will give you a list of matches: other people who tested with that company and who share DNA with the descendant. If you do not have a candidate for the father, you cannot actively select the people you want to compare with, but you see which persons just happen to match and work from there.

  • Y-DNA testing. If the illegitimate child is male and you test a strict male descendant, his Y-DNA matches may show several people who share the same surname. This may be the surname of the father too, especially if this matches one of the known men in the mother’s life.
  • Autosomal DNA testing. You want to test the oldest generation of descendants of the illegitimate child (or the illegitimate child him/herself if still alive and willing to test). To eliminate any matches from the mom’s side, you also want to test the mother or relatives of the mother who are not also descendants of the father. Any people who match the mother’s relatives can be eliminated from the list of matches. For the remaining matches, look for clusters of people that match each other on the same segments: those segments may have come from the unknown father. Then compare trees and see if these people share common ancestors. Since you are depending on the willingness of strangers to share information with you, this can be a long and sometimes frustrating process. But the numbers of people getting tested are growing quickly so there is a great potential for matches out there.

For more information about using DNA testing for genealogical purposes, I refer to Roberta Estes’ DNA Explained blog.


Finding the father of an illegitimate child is one of the hardest genealogical puzzles to solve. Often, the identity of the father will remain unknown but in some cases, enough evidence can be found to create a theory or even prove it.

Rarely are these cases solved by applying just one strategy. Developing good candidates for the father is often the result of extensive research into the records of the mother, child and potential father and acquiring detailed knowledge of the community that they lived in. Combining these traditional research methods with DNA testing can help to prove a theory.

Do you have illegitimate children in your family tree? Have you ever been able to find out who the father was? I would love to hear your strategies so please share them in the comments.

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