I was having a discussion with a colleague about identical twins. If a man were to impregnate two women who are identical twins. In terms of genetics and DNA, the children would be more like siblings rather than cousins right? My colleague disagreed w/ me but I stand firm.
Definitely closer to siblings than cousins. They have one parent who is the same and the other is basically the same. Cousins have parents who are siblings and a complete different parent. Their DNA is probably substantially different. In a legal sense, they'd be half-siblings and cousins?
Definitely siblings regardless (as mentioned above), but it also depends on the sex of the identical twins, I mean unless all boys/all girls out of the 2 pairs. This could give a bit more genetic variance if one pair were girls (using the guy's x chromosome), while the other set were boys (using his Y). Regardless though, siblings still, (especially with genetic crossover) regardless of x/y being used. So not sure what the argument was on cousins later down the chain.
They would be indistinguishable from siblings, but technically they'd still only be half-siblings and cousins. They are cousins (not half cousins, which isn't a thing) as that condition only describes the relation of one parent. There is such a condition as "double cousins", when a pair of brothers marry a pair of sisters, though I imagine it doesn't get much practical use in this day and age. These words describe concepts that were around since language was invented. At that point, genetics weren't even something that could have been imagined. Therefore, genetic sequencing can be used to provide proof, but the words themselves don't have anything at all to do with genetic makeup. They only indicate which combination testicles and ovaries you originate from, relative to another person. Not strictly germane, but this was a hit back in the 40s for Phil Harris, who voiced Balou in the jungle book:
Two children by the same man are siblings .. . . . yes? Now If Two Identical Twin men . . . impregnated Identical twin sisters. . . . . .. . . Rocket River
Frank: Let me understand. You got the hen, the chicken and the rooster. The rooster goes with the chicken. So, who's having sex with the hen? George: Why don't we talk about it another time? Frank: But you see my point here? You only hear of a hen, a rooster and a chicken. Something's missing! Mrs. Ross: Something's missing all right. Mr. Ross: They're all chickens. The rooster has sex with all of them. Frank: That's perverse!
If Co-joined identical twins have sex with identical conjoined sins....you have a porno. Or you get really good burger joint.