There's no established evidence that sexual preference is inherited in any way. there is however evidence that suggest that neonatal stress contributes to a dissociation of sexual affiliation from biological gender(transexuals). The one thing that is pervasive among both dominant and passive members of gay and lesbian relationships is the significantly higher incident of childhood sexual abuse.
this is why the highest rate of domestic abuse is among lesbian couples and the highest rate of gay pedophilia is among those sexually abused at a young age.
In other words, while homosexuality may not be a choice, it certainly isn't inherited and is grounded in biological and/or psychological trauma.
There's nothing inherently wrong with voluntary sexual activity between consenting adults, but there is something foundation immoral about ignoring the trauma at it's foundation.
Further, it's impossible to provide optimal physical and psychological health to a child without a mother and father.
The optimal nourishment for an infant is being breastfed directly from the mother from birth to 12-18 months on demand and the safest household condition for a children are with married biological mother and father.
Growing up without your biological father is particularly damaging to children due to a variety of factors.
There's no way to achieve this with 2 women or 2 men as parents.