I don't think it is our right to define a family strictly as that which is shown above. So, two lesbians who love each other want to be a family, let them. Or two non- lesbian women who never married decide to rent a house, can they not be each other's family? Family doesn't have to be limited to just those people that came from the same womb.
To further illustrate, let's take our two straight women who, for whatever reason, never found "the one" in life. So, they decided to rent a house together and live as strictly platonic companions. Why can't the one share her health insurance with the other? Or her discount at her job, or whatever it is that's important? They have no other beneficiaries, they are alone in the world, save for this person.
Everyone should have the option to be "married" in essence to whoever they want, and be able to share what they have with the other, regardless of their gender.
And this whole deterioration of the sanctity of the family? It's complete bull! When was the family actually sanctified? It's always been such a dysfunctional entity! Dads running out on their kids for the secretary, the wife living as a personal assistant to her husband, etc. Kids disowning their parents or stealing money for drugs? Yea, dysfunctional! So why can't people who care about each other be a family?
I think the definition of family needs to change hardcore. If you believe in having 20 kids and having a nuclear family, then by all means, go for it. However, if you're not "typical", why not define your own family? Everyone deserves a life long companion. What goes on in the bedroom is no one's business. Really, it's not.
Also, confining family to what it is today prevents us from the potential relationships we could have with people all around us. If we confine the definition to just those who are blood or marriage related, we alienate ourselves from other people in our world, thinking they're not as good because they're not one of "us". But aren't we all brothers and sisters anyways? So by being exclusive, we aren't able to serve one another as lovingly as we could if we considered family to be everyone.
I know this is a totally sensitive subject for some people, but for me it just makes sense. And in a hundred years they're going to look back and say "I can't believe that back in the day family only meant a man and a woman who have sex!" Because family is going to be open to everyone. It's gonna be a great day!