Twins

So I have history of twins from my mums side of the family. My elder sisters are twins.

Now I have a 2 year old son already. And I want to get pregnant again but this time my husband and I want twins.

So I want to ask, is there anything i can take to aid the conception of twins?

I cant do hospital fertility treatments because they are expensive here in Nigeria.

UPDATE

Thanks so much for responding to my post guys. I really appreciate it.

My husband and I have decided not to try any medication. We will just try naturally and see what happens. If it's a singleton we will love him or her no matter what.