Teenage Sex - The Sleepover Question
nytimes.com
nytimes.com
However, as you note, age of consent is a very important factor. The two families could be enlightened, mature and responsible, but if either kid is below the age of consent, then both kids are at risk of being registered sex offenders, and the enabling parents may be in for legal trouble also.
I would prefer to take the Netherland's approach, but the legal issue trumps everything, in my opinion, in these hyper-puritanical United States.
You're right...these laws were likely written during a more conservative age, but even though attitudes have changed, it is difficult to change the laws. Just do a search for "Blue Laws" to see plenty of examples of this. I think that it's quite possible that now the situation is reversed, that the laws are influencing attitudes. Just look at the drinking age. I'm sure there are plenty of parents who don't give their kids wine simply because the drinking age is 21.
I know I don't particularly like to be judged on things I did before I was 19 or so, because the me at 18 was a very different individual (less responsible, more petty, etc.) than the me at 20. So, turning the question around: are you seriously going to judge a person based on what he/she did a number of years prior?
The way I read the article is "Teenagers are going to have sex. Parents can either treat their children with respect and become emotionally closer with them by acknowledging this and accepting it, or pretend their children aren't sexually active and cause both parent and child to become more emotionally distant from the other."
I see the attitude taken by the Dutch family similar to the approach I see many European families taking towards alcohol with youth. If children are shown alcohol is something neither dirty nor evil but rather something to be enjoyed in moderation, the child is more likely to grow up respecting and enjoying alcohol and less likely to abuse it.
Same with sex. If a child grows up with his closest role models showing sex isn't shameful or evil but instead natural and wonderful, he's more likely to grow up and have mutually respectful relationships.
At some point—probably around age 16 to 17—everyone is someone's sloppy seconds. One either deals with this essential fact... or doesn't.