No, you have to then average. That is because kids with lesbian mother are 100% and the kids with gay father are another 100%. Look for example at the voting numbers: they would add up to more than 100%.
If we average columns 2 (Lesbian Mother) and 3 (Gay Father) we get:
Ever touched sexually by parent/adult: (23% + 6%)/2 = 14.5% children of a lesbian parent, custodial or not, report that. In intact heterosexual households the figure is 2%
Ever forced to have sex against will: (31% + 25%)/2 = 28% children of a lesbian parent, custodial or not, report that. In intact heterosexual households the figure is 8%
Note also that it does not say that the molesters/rapists were homosexual or even parents. It does not say if the rape was while still minor.
2 x children of a lesbian parent, custodial or not, report that
2 x children of a homosexual parent, male or female, custodial or not, report that
It does not say if the rape was while still minor.
But it does say that it was forcible rape ("forced to have sex against will"), so it does not count consensual sex between a minor and an adult legally considered rape.
Note, too, that the distinction is further blurred if an adult approaches a minor who has been groomed for such sexual contact; if the parent is the one doing the grooming his chance of success is good, so there would be rarely a need to force anything, and such cases are not reported in the table.