Marriage is not a contractual obligation to infants. The obligations that parents have to their children under the law exist whether or not those parents are married.
Using tax incentives, states encourage marriage to bond mothers and fathers in a permanent way (an incentive program). No incentive program is 100% successful, but it is better than sentencing children to life without the possibility of having either a mother or father. (gay marriage). Even single parents present the hope of one day providing the missing parent.
Why do states incentivize it with tax breaks? So that adults can shack up and escape paying taxes; all for stripping children even of the hope of the missing parent in their lives? No, the states incentivize mother/father marriage because they get something in return. They get boys with fathers and girls with mothers so that these poor souls don't grow up to be statistically "lost" in their formative years and turn to drugs, depression, suicide, indigency and prison as result.. PRINCE'S TRUST 2010 YOUTH INDEX SURVEY
None of what you just posted makes marriage a contractual obligation to infants. Nor does it address the fact that the legal obligations of parents to their children exist whether or not those parents are married; nor does it address the fact that tax incentives for children exist whether or not the parents are married; nor does repeating your lies about the Prince's Trust survey make them any more true than in the past.
And Silhouette ignores that those were the arguments made by States before- the arguments that lost in court- over and over.