[Nowhere Man]

If a girl is old enough to get an abortion without her parent’s consent, then why ought she seek parental consent to purchase alcohol?

Again, it depends on the law in that State. I'm pro-life BTW but under the Constitution, it is silent on the issue so it is (or should be) left up to the States. The only way the Feds can get involved is if the Constitution has been amended to address the issue. It's like Dred Scott, the decision, as terrible as it was to may, was most likely the correct one because it was before they amended the Constitution with the 13th, 14th and 15th Amendments.

[JCBreckenridge]

The 14th explicitly rules out state regulation wrt personhood. A state cannot pass a law that would permit one person (the girl) to take the life of another (the unborn child). Thus, parental consent is irrelevant. Consent could not be given for that which requires taking the life from another person.