@hawkeye10,
Would support 13 for the US national AoC. With the proviso it be for those with 2 years of each other. Know there's 3 to 5 years close in age examples but usually teen peer groups are going to be only a year or two apart as with people in the same grade so think that's more than sufficient.
A counter proposal is patterning our system after Japan's where there's a AoC for sex with anyone, then a lower one for with parental-consent. We already have this in the US but with the stipulation you must get married. Here, if you marry you're then exempt from the. As here in Missouri the regular AoC is 17, but can marry at 15 with parental consent, and once you do the AoC is retroactive to the age of marriage so 15. And there's provision for approving even younger marriages with judicial consent as in Massachusetts where 12yo can marry with a judge and parents' permission. Dunno how, when, or why that ever comes up but it's there.
Keeping our AoC in the 16-18 range just makes the sex illegal and thus covert. Doesn't prevent or discourage it though and so costs the state and people involved money. If you lock up an adult male who gets a minor woman pregnant, he obviously casn't provide for his family paying child support. Decriminalize the ages involved and he can. Since a major component of the AoC laws are costs to the state when young women get pregnant, drop out of school, go on welfare, etc. the solution's obvious - quit locking up the fathers.