Jus want twins

Luck

Yep... as Curlyben said, luck is the factor most of the time. Even if twins run in your family, there is nothing you can do to make it happen.

There has been some talk on eating wild yams, (this is not the sort you would find in most supermarkets), but the issue may indeed have more to do with genetics for the particular group of people that this has been seen in.

Other option of course is IVF... often 2 or 3 embryos will be implanted and can increase the odds of twins. Costly way to up the odds of twins and not really feasible if you don't have fertility issues.

Hyperstimulating ovulation with meds may increase the odds, but again won't be feasible if you don't have fertility issues and no credible doctor would prescribe for you and wouldn't be a guarantee anyway.

So it comes back to luck for most people.

Yes as noted do twins run in you family, if so how many sets.

But it is just a matter of luck.