Nope but it occurs to them once or twice. And that's enough to seal the damage. As they grow, they learn about biology and how two men using each other's anuses as artificial vaginas is aberrant sexual behavior therefore. So in the aging child's mind there grows a disturbance. They become aware that their "two dads" or "two moms" aren't quite playing with a full deck. And that will cause a rift as those "parents" keep insisting against reason and science
"no no...this is normal..really...we swear it is."
As the child becomes an adolescent, the child will find the dildo under the lesbos' bed and start thinking
"hey, wait a minute...". And the child of two gay men will realize as sophistication grows in his mind that a man using another man's business end as "just another hole" is...
"hey, wait a minute..." when he thinks about biology.
The whole thing is set to unravel in the child's mind at a given moment when he or she realizes that their "parents' are really two crazy people of the same gender trying to approximate an actual heterosexual relationship. Especially if one of them acts male and the other female, no matter what the gender is in question. We've all see that too. Are you going to insist that doesn't exist? The butch/femme thing in both gay males and lesbians? How they always seem to gravitate towards those roles or each other in the first place?
You might fool some people. But you won't fool a child. And when we remember we're talking about a normal childhood under a marriage contract; the "gay marriage" is not only not normal, it is mind-*******...damaging to any children involved. The ruse can only last so long. "Through the mouths of babes" comes the stark and uncomfortable truth.