The boy may also have been molested by his homosexual adoptive parents. The incidence of that is very high.
I find it offensive that if there is no evidence of such, you immediately all go there and assume that because they are gay, it is their fault they were stabbed by their child who was adopted as a child.
If you are using math, the fates of family members begin injured by an adopted-as-an-older child are more risky than the rate of children molested by their gay parents. But we see here the rush to convict the victim because gay = icky.