Assassin's Creed 18+ rating?

My kids are enjoying the first Assassin's Creed game, and would like to play later sequels in the franchise.

I've found the Heritage Collection on Amazon, which has quite a few Assassin's Creed games on it:
http://www.amazon.co.uk/dp/B00FOGFP0A/?tag=brite-21

However, a couple of the later ones are rated 18.

Is this just because of violence and gore, or is it due to sexual content?

The violence isn't too much of a worry as they're already used to Oblivion and Skyrim. However, sexual content would be a concern.

Any pointers much appreciated.

(PS - this is not a general discussion thread about sex and violence in games - just about the reason for the 18 rating on later Assassin's Creed games. )

Not a gamer myself, but I found your query interesting Brian. And it seems their may be a solution for you:

It was a huge shock for me to read the reviews here, buy the game online, and when it arrived it was rated for 18 + in my country. And it deserves that. But then I saw you can use settings on the PS3 to tune the game to the age of your kid. That way the game is just as fun, just as scenic (a wonderful game really), without horrible gore, and constant swear words. Buy the game for your kids if you can find out how to change the parental control setting on your PS3

Click to expand...

This is in reference to AG IV Black Flag

So that suggests it's to do with gore and swearing but that you can tune it out in some way.

Interesting - I had no idea there were Parental Settings for games on the PS3!

No sex. The one time when it was intimated, it faded to black...

Vertigo is right. It's more the language, but it's not gratuitous.

You know I'm a hopeless AC fanboy? I even have the (dreaaaadful) books. I just started playing Unity which is phenomenal. Just beautiful. Also full of bugs.

pH