Answer:
False.
Step-by-step explanation:
This is completely false, by doing this those parents are incurring in illegal activities.
About the consent of having sex, there's no law that established a specific age to participate in sexual relations, but the law does specify that for every person with 18 years old or older, it's illegal to have sexual interactions with a minor, no matter if the minor want to or give consent to such actions. Either case is always considered child abuse, the law automatically will treat the minor as a victim and the partner as the offender.
The law is clear, even parents cannot consent this sexual encounters, they easily could be sued.