Paternity claims, maternity claims and custody fights are commonplace in Texas family courts and elsewhere, but a case in Houston may take the prize for complexity and uniqueness. A woman there wants custody of twins even though, genetically, they are not hers. The father, who is a genetic parent, says the woman was a surrogate who simply carried the babies to term. Not so, says the woman, and she wants co-parenting rights with the father who is gay and has a male partner who also wants to be part of the family. Some experts say this could be a landmark case that defines what it takes to be considered a mother.