The bill of rights gives us the right to life, liberty & the pursuit of happiness (understood as property)  in that order.  So, whenever there is a conflict between rights, the conflict necessarily has to be resolved in the same order.  W/out life, there can be no liberty or pursuit of happiness and w/out liberty there can be no pursuit of happiness.   An obvious example was the slavery issue.  One man's right to own a slave came in conflict with another man's right to freedom.  We see how the proper order of rights was necessary to resolve this issue.

Forcing sexual orientation rights in this regard would put the rights to have a child (pursuit of happiness) over the right to liberty most specifically in that it restricts religious liberty of those to object based on religious beliefs.  Or in fact the child might have a religous belief that opposes having same sex parents.  What if the child doesn't want to be forced into a family w/out a mom and dad?

Those in favor of same sex marriage will argue this is their right to freedom as well. However, their right to adopt is no different than a single person who wants to adopt.  Adoption agencies can freely "discriminate" against sending children to this environment and to take into consideration "family status" which this law would restrict.  This regulation would restrict the ability of those seeking to place children in what they feel or believe--based on religious principals--is the best stable environment for children.  Once we take away this fundamental freedom, we destabilize our entire society.  

If we grant special status to sexual orientation outside of marriage between a man and a woman, then anything goes.  Do we apply that same standard for polygamy, incestuous marriages, child molesters who will argue they were born oriented sexually towards children?  This language would prohibit an adoption agency from taking any of these factors into consideration when choosing an environment.  To accept this legislation would be to accept that same sex couples' right to a child (pursuit of happiness) tramples other individuals right to religious liberty.  It tramples the right to religious freedom for both the adoption agencies and the children who may object themselves.