We're told the government has the right to force us to wear seatbelts because the injuries sustained without them have a public health impact. We're told that tobacco can be banned and alcohol taxed because they have public health impacts. We're told that guns should be controlled because their misuse has a public health impact.
Yet acts that clearly have a public health impact -- promiscuous sex, homosexuality, even polygamy -- are not only not permitted to be regulated, they are encouraged in every forum from our pop culture to the public schools.