# When the father is someone else **URL:** \ **Category:** Factual Questions\ **Created:** [July 29, 2011, 10:18am UTC](https://boards.straightdope.com/t/when-the-father-is-someone-else/590724 "2011-07-29T10:18:22Z")\ **Posts on this page:** 4\ **Page:** 3
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [July 30, 2011, 3:18pm UTC](https://boards.straightdope.com/t/when-the-father-is-someone-else/590724/41 "2011-07-30T15:18:32Z")
> [@septimus](#): > > We tested our own blood in a high school science class; I showed AB. My Dad’s dogtags from WWII show Type O. For many years I assumed I’d fouled the high school experiment; I eventually retested: again, AB. Yet, I know my Mother; and I know how much I resemble my Father, not just physically but psychologically. > > We can’t test him, but I guess it would be easy to arrange to test my much-younger sibling and I to determine if we share one parent or two. > > I’d bet a substantial sum that we’d “pass” the test; that my Dad’s Navy blood test was faulty. Well, what’s your mom’s blood type? It’s perfectly possible for an O father to father an AB child with an AB mother. Some of their kids would be expected to be A’s, some B’s and some AB’s. You wouldn’t expect any O’s at all, though. Also, remember that all these blood types refer to proteins found on the surface of the blood, and are caused by mutations in people’s DNA. It’s theoretically possible for a fertilized egg to develop the mutation that causes A and B antibodies spontaneously - after all, the reason we have them in our population is that, at some point, someone’s DNA spontaneously mutated to make it happen. Granted, it would be pretty unlikely for both the A and the B mutations to happen to one person spontaneously, but if your mom is an A, you could inherit that from her and be a spontaneous B mutation, making your blood AB. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [July 30, 2011, 3:31pm UTC](https://boards.straightdope.com/t/when-the-father-is-someone-else/590724/42 "2011-07-30T15:31:20Z")
> [@WhyNot](#): > > Well, what’s your mom’s blood type? It’s perfectly possible for an O father to father an AB child with an AB mother… > > … are caused by mutations in people’s DNA. Mutation is possible, but my bet would be on a dogtag mistake. As for an O-type to be able to father an AB child without mutation, my Mendel’s Laws are rusty, but I’d be willing to place a bet against that proposition also. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [July 30, 2011, 3:41pm UTC](https://boards.straightdope.com/t/when-the-father-is-someone-else/590724/43 "2011-07-30T15:41:18Z")
> [@Omar\_Little](#): > > Even if it’s 5% of the general population suspect it, then only 0.2% of the general population have an incorrect paternity. I did some digging for cites in a previous thread im having trouble finding now but several reliable looking studies ran 3%-25% mainly varying with socioeconomic class. The weighted average they gave was like 7%. Its not much of a stretch to imagine that 7% of sex is with the non obvious partner therefore 7% of the children concieved were fathered by the same non obvious partner. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [July 30, 2011, 4:22pm UTC](https://boards.straightdope.com/t/when-the-father-is-someone-else/590724/44 "2011-07-30T16:22:05Z")
> [@septimus](#): > > Mutation is possible, but my bet would be on a dogtag mistake. > > As for an O-type to be able to father an AB child without mutation, my Mendel’s Laws are rusty, but I’d be willing to place a bet against that proposition also. :smack: Of course, you’re right. I forget the A and B from and AB mom would be on different gametes. Duh. Yeah, probably a tag error. At least it was in the safest direction possible - better than being a O type labeled AB if you need a transfusion! :eek: [Previous page](https://boards.straightdope.com/t/when-the-father-is-someone-else/590724.md?page=2)