The number of children that one passes through the vaginal canal during the birthing process WILL eventually affect it's elasticity.
I dont see how the number of sex partners or even sextoys could have a remotely similar effect. Unless, of course, one is "playing" with a bowling ball.
Age has bearing as well. We all lose muscle integrity over time as part of the aging process. But the effects of that are not seen until one is very advanced in age, I should think.