Despite my previous quotation of Mr Larkin, we have procreated and have one of each: boy 12yo and girl 9yo. Both are in boarding school and the boy has just moved up to a boarding house with older boys (up to 16) so Memsaheb insisted I had "the talk" with him before he started back so that he would not be freaked out by the older boys' banter and personal habits.
A longish drive with just him and me to get some privacy from the womenfolk proved to be a decent environment for the birds and bees nonsense and a quick overview of teenage personal time. Slightly awkward but seemed to work out. I told him to ask me any questions rather than his mother (we have a deal that she will do all the girly stuff with Tiny Temper when the time comes). Alongside the "facts" I gave him the rules:
Rule 1 - don't be a dick. This applies to family, friends and strangers equally. Twats get what they deserve.
Rule 2 - be good to your mother. I know boys are twats as I used to be one, so I can ignore stuff that will send his mother into orbit.
Rule 3 - everybody fights, nobody quits. Effort scores more than results.
As an aside, the only advice I give my airpersons is "Never say no to an offer without good reason, it might not get made again."