"I blame the grandparents" was a slightly tongue in cheek variant on "I blame the parents", but generally I would be a Nurture over Nature person.
I also take your point about the increasing secularisation of societies all over the developed world, only 2% of the UK population are practising Christians ie church attenders. However, lets not forget that some of the most debauched periods in history were at times when religion was a major part of society and the state
However I believe that society itself is now a huge factor in affecting the upbringing of a child. It is difficult to deny a child all the things it's peers have, all the sexualised barbie doll versions, watching female role models in pop music writhing around on MTV in fetish gear, clothes that are far too "old" for them and so on.
Recently I saw pole dancing classes being advertised as a great fun form of exercise to combat childhood obesity!
I am by no means a prude. I have liberal views on sex and I think pornography has a purpose and a place but sexuality has crept down from the top shelf to kiddies pop magazines and toys and is widely seen in advertising aimed at young people.
It's a shame they can't spend their childhood playing games rather than thinking about getting a tattoo and breast implants.
In the US and some European countries pornography became legal to make and possess under civil rights legislation. Now with the internet it is unstoppable even in countries where it is illegal.
Parents can only hope to teach their kids about love and romance as the most important part of a relationship rather than the mechanics of sex.
Christina Aguilera has a powerful voice but is encouraged to dress in clothes that take their cue from pornography and fetishism to sell more records. There's currently a pop song about sending "dirty pictures" on a phone to each other. I don't want to demonize Christina Aguilera, they're all at it.
I suppose, in the end, sex sells, it shifts products from cars to life insurance.
So, I blame capitalism.