I suppose with your wider point you're referring to homosexual parents aren't ya?
Am I wrong or am I right?
Amongst other non-traditional forms of relationship, JJ; yes.
Anyway I think the commentators are referring to families where there is strife and abusive behaviour - from either sex.
And I would understand them to be referring to the importance of a gender balance within parents, in addition to the detrimental nature of strife and abuse.
I am by no means the only person who believes that Zachary Furnish-John is little more than totem child, who shares his "parents'" names but, at least until he is 'house-trained', is not actually central to their respective lives - in much the way that the children of grandees have often had little more than such symbolic value.