Want to marry my sister

you can not marry a sister which illeagal & void.

IMPOSSIBLE. ILLEGAL, VOID,

What if we both Convert to Muslim ? Will it be okay ? And we both can wait till she is 18 .

We both love each other very much & willing to stay together for rest of the life. Please help.

immoral person.

should be banned from LCI

@ Author..

Reconsider your decision, thats may b just a attraction not a love. Respect moral values of your family and even society. You are not going to get any respect even after marry that girl. Stay away and do your studies or work watevr.

Adv. Neha

As per Islamic law, you can marry your paternal uncle's daughter on the other hand, Hindu law is against this. Even assuming that she is not your paternal uncle's daughter and some other Muslim girl, you have to first decide that its just infatuation or love. If you are very confident in your decision and would like to marry her having least concern for the issues which you will face in the future, you may go ahead after she attains 18 years. 

But...

In my opinion, if after marriage if you feel that it is only infatuation and not real love and you feel guilty since you became a convertee of other religion, making that girl also a convertee, and you feel that you have committed a big blunder, by that time i dont think you will have anything to lose. 

Moreover i have heard of many people whose marriage is a love marriage and particularly against their parent's wish, having a lot of difference of opinion after marriage. Here if you decide to marry her, your Hindu law will not permit, so you and herself have to get converted to Islam, then marry her and fight against your parents. This will create a lot of complication.  

So think  and decide. This is life and not just a thing which can be returned or corrected easily. 

Heed the warnings of these learned Advocates.  Marrying your first cousin is prohibited under Hindu Marriage Act 1955.  The fact that you are asking will there be any legal consequences means you are fully aware that you will be breaking the law.

If you ignore all this advice and marry this girl, you will also run the risk of congenital anomalies (birth defects such as intellectual disability) if you have any children together.  Please read the attached fact sheet link from the World Health Organisation website to confirm this. WHO are an official healthcare body.

Just move on with your life and marry a girl who isn't related to you - and let her find happiness elsewhere too.  For god's sake, she is only 17 years of age - she's just a child!

https://www.who.int/mediacentre/factsheets/fs370/en/