Sunday, January 30, 2011

Punnett squares.

In my tenth grade biology class, while we were learning about genetics, our teacher gave us an interesting take-home assignment. It was a list of genetic traits where the inheritance is relatively simple in humans--attached vs. unattached earlobes, curlable vs. uncurlable tongue, that kind of thing--and instructions to document which we had and which each of our parents had.

The awkwardness this might cause adopted kids, or kids who had no contact with one parent, was evident at the time and the teacher did kind of skate around it with a "well, just list your traits if there's, like, an issue." But I didn't realize until just now why else it might have been a bad idea.

"Mommy, if you're blood type A, and daddy is type O, why am I type AB?"

Whatever it is that you might find out about your family, that's a hell of a way to find out.


  1. Friend of mine had that exact situation. Her mother (father wasn't in the room) said, "Well, I know you're mine."

    As an adult the friend is pretty damn pleased to have proof her father isn't her biological father; I gather he's not exactly a winner of a human being, and is long since divorced from her mother.

  2. oh geez. when we did that in MY biology class, we didn't list/weren't instructed to list our parent's. we just talked about it.

    it was noted that i have both a free and an unattached earlobe. mutant ears ahoy!

  3. I had this happen, actually, with a Punnett square on blood types. My teacher took me aside and explained that the typing test wasn't 100 percent accurate and that blood types are more complicated than Mendelian genetics. (Yes, we played with blood in high school Biology. And we liked it.)

    Whether or not she thought she was bullshitting me, given the rest of my traits I don't doubt my paternity.

  4. Bruno - My traits actually didn't totally work either (so I falsified the results so my teacher wouldn't think I was a bastard). But I'm a dead ringer for my dad's mom, so again, probably just that human genetics are a lot fuzzier than pea pod shapes.

  5. Worst case scenario: "Oh, well that's because he isn't your father. I mean have you heard him speak? Not proper genetic stock by any stretch of the imagination. I just keep him around for the sex."
    Honestly this doesn't sound that bad in my opinion, but I've never considered that whether or not someone was a sperm donor had anything to do with them being a father.

  6. I think you can look back on things like that as an adult and say it doesn't matter - a father is someone who was there, who loved you, not just the sperm donor - but as a teenager grappling with your identity it's hard. We all like to know where we came from. I know I struggled a lot with that as an adopted kid.

  7. I think it's okay to decide that you consider your family father more important to you than your biological father, but I'd probably be upset if I found out that I was lied to and not given the chance to make that decision.

  8. People should be aware that there is a rare mutation called "Bombay" that mimics type O even if one has the genes to be something else. So ABO is *not* a reliable test of paternity.

    I work in a genetics department though I am not a clinician, and once had a seriously scary phone call from someone who wanted to know whether the newborn in the hospital was or was not her boyfriend's. I tried hard to get her to call a genetic counselor, but I don't know if she did. I was *very* careful to give no opinion at all, because it could be Bombay, it could be a typing error (I thought I was type B for years due to high school genetics typing, but the blood bank says I'm A and they are surely correct), it could be any kind of confusion, it could be nonpaternity, but in *any* case it could get someone dumped or sued or shot, and I don't want to be responsible for that.

    Me, I am not the biological child of my father nor the biological parent of my son, but it's no secret in either case. I think it's the secrecy rather than the nonpaternity (or nonmaternity in my case) that does harm.

    My husband's and my marriage agreement explicitly included "any child of either of us is our child." Never had any birth children to test it, though.

  9. We had a case like that in my high school science class. It turned out he was adopted and his parents had never told him. He took quite a downward turn for a while after that.

  10. Hershele OstropolerFebruary 4, 2011 at 12:35 PM

    My stepdaughter is doing a unit on immigration and all I'll say is, it's a good thing she's still in contact with her father, so the family history thing is merely inconvenient (since he's a couple of time zones away).

  11. As a kid, I wasn't in contact with my dad but paternity wasn't an issue (Dad - moustache + boobies = me) and I couldn't really go beyond eye color in said activity. As a biology teacher, I try to keep that in mind and will occasionally use a kid as an example if I know the family and they're the fucking Cleavers. You're supposed to do shit that kids can "relate to their lives" but, yeah, that's a helluva way to cast doubt on your family lineage. We generally have set examples and the kids that are interested can apply it to themselves, if they feel so inclined.

  12. I have a friend who learned she (and her sibling) were donor-conceived because of a high school Punnet square. She then had the awkwardness of knowing while her parents didn't think her sibling was yet old enough to be told. I'm not sure if she'd ever have been told, or maybe not til adulthood, otherwise. It's had some health history impacts for her, but otherwise, her dad's her dad who raised her. But yeah, finding out via a bio class = awkward and uncomfortable. OTOH IMHO by high school a kid deserves to know their genetic composition.