I'm not a parent and my parents whould have passed out if I asked for a opposite gender sleep-over. But I was a step Mom and my ex-husband had two kids, 11 y/o girl and 14 y/o boy when we first met so I got to go through the teenage years with them. My Ex was a developmental psychologist and his philosophy was teaching the children about safe sex at a young age, open communication and helping them be safe. His position was that statistically speaking the majority of teens are sexually active by the age of 16 whether you want them to be or not and you can either be an ally and help them stay safe or they are just going to do it anyway without your input. Having said that, neither of them asked for opposite sex sleep-overs until they were at least 18 years old. Then they didn't really ask, because it just wasn't really a big deal.
Living life like there's no tomorrow.
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2007 Look Dura Ace
2010 Custom Tonic cross with discs, SRAM
2012 Moots YBB 2 x 10 Shimano XTR
2014 Soma B-Side SS