Is there stats on the ratio of birth illegitamacy for any country?
Yes. Easily Googled it.
Surprising that in most countries that are not strictly religious, the percent of out-of-wedlock births is quite high. You can also find comparisons with 20 or 50 years ago, and (no surprise) it has grown dramatically.
What I did find surprising was the high ratio of such births in Latin American countries, especially Chile and Argentina.
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I’d quibble with your use of “illegitimacy”, both in connotation and denotation. Denotatively, children born to unmarried parents aren’t outside of legitimacy by law–at least, not in any legal system I know about. Connotatively, “illegitimate” is an ugly word to attach to a baby.
That said, check out “births outside of marriage”
Sorry. No excuse for that mistake.
Good point. Back in my home jurisdiction all distinctions on legal rights of children by marital status of parents were done away with a lifetime ago. No more legitimate, illegitimate or “natural” children, just children. The statistics are kept for the sake of ensuring child welfare follow-up.
Most U.S. states distinguish between children born of a marriage and those born outside one for inheritance purposes. But those distinctions generally vanish for “acknowledged” children regardless of whether they are adopted by the putative father.
To answer the OP: data for the U.S. is here: Births to unmarried women U.S. percentage 1980-2021 | Statista… The ratio hovered around 40% of births for most of the 2010s, which seems high but I’m not spending a lot of time in maternity wards.
Yes, the distinctions are much different too because so many “children in single parent households” are the result of marriage but now the parents are divorced. Plus so many people “live in sin” ( 
) nowadays, so there’s not that much distinction in the child’s experinece between them and the parents who are married and still together.
I suppose the question is more along the lines of “what particular childhood experience are you trying to distinguish?” Parents who separate/divorce before the child id old enough to know, are a different childhood experience than those who are separated/divorced once the children are school aged. Children born “out of wedlock” are not necessarily the product of irresponsible sexual behaviour nowadays. Even teen pregnancies have to tak into account couples who cohabit or marry early.
Oddy, I wasn’t aware there were disctinctions about inheritance. I suppose some US states are weird like that. There is the legal assumption a child born during a marriage is automatically legally assumed to be the child of the father. Can a father disinherit a child of marriage based on a DNA test? I know technically with a will you can disinherit anyone, but what about intestate inheritance??
I don’t know your home jurisdiction, but my guess is that the marital status of the parents would still matter for paternity. In most jurisdictions, a child born to a married woman is automatically presumed to be the husband’s, whereas in case of an unmarried mother, an acknowledgment of paternity would be required. Such an acknowledgment is not a major bureaucratic act, but it might still be necessary.
I assume nowadays a DNA test is equally valid to establish paternity. I guess the question is whether a test involving siblings, after the father has died, is accepted by the courts in an intestate estate debate?
Although for wills, I recall a discussion on wills that said not mentioning a child can get a will invalidated (“was getting old, forgot…”) so the will would have to explicitly exclude any valid claimant.
Yes, but it has to be done early in the child’s life. Basically, if the father thinks it might be somebody else’s baby, the onus is on him to get a paternity test.
And he’d better do it by his state’s deadline, which is probably earlier than you’d guess. He shouldn’t guess what “early” means.
The CDC/NCHS also has stats. Here is one such paper. (Coincidentally, I was a childhood friend of one of the authors (Brady Hamilton). He lived five doors down from us. He has authored many papers on this subject.)
Sure, but it can be a heck of a lot of (costly) litigation if the alleged father contests it. In case of a married mother, the presumption of paternity applies automatically and will remove the need for such litigation. In legal proceedings, being on the favoured side of a presumption can make all the difference.
A friend of mine paid child support for 18 years to his then-separated and eventually divorced first wife. The child in question was very obviously fathered by someone of a very different ethnicity than my friend who was the legal husband on the kid’s birth date and on any plausible date of conception. DNA testing may have been needed to establish who the father was, but a mere glance would establish who the father definitely wasn’t.
Presumptions matter. So do deadlines. Facts he learned about waaay too late. Oops.
Thank you. Criticism noted. New to site, was eager to try. No offense taken.
England & Wales statistics are here Conceptions in England and Wales - Office for National Statistics
Yes, I recall an article about the Welfare Department for California -the article alleged that the department deliberately nisdirected mail aimed at deadbeat “fathers” so that they missed the deadline to contest paternity. The law, written before DNA, said the alleged father must contest paternity within 2 years of the child’s mother filing for child support - something the department on her behalf did if the mother applied for any benefits. For example, they used outdated addresses (despite up to date addresses being in the DMV database), and several other tricks. Once the two years were up,there was no way to challenge paternity, even if DNA proved the child was not his, even if the woman was outright lying (one man had been out of the state for ayear or more when the child was conceived). The law is the law. At the time, the law made sense - they didn’t want someone challenging paternity over and over, every time the child support issue was reviewed in court.
It’s surprising just how high the proportion of births outside of marriage is in some fairly well-off countries. There’s a common belief in the U.S. that having a child outside of marriage is something more common in poorer families. But consider Iceland, for instance. It’s a fairly well-off country with a proportion of 69.4% children born outside of marriage. According to many websites on visiting Iceland, it’s common for a couple to meet in a first date, have sex afterwards, get to know each other on later dates, then move in together, then have children, then finally get around to getting married.