i have selective mutism myself and there is really no cause for it other then you have it in your genetics

Selective mutism is when someone talks in some situations, such as at home or with their best friends, but can't talk in others, like at school, due to anxiety.

You can get more information on wikipedia's selective mutism article and at selective mutism.com.

Hope this helps!

The most reliable place to learn about selective mutism is from a local doctor or medical specialist, due to the range of possibilities associated with that disorder.

Selective mutism is basically social anxiety. After you get past the first few stages of meeting someone, in any relationship, they open up to you fully. Same with someone with selective mutism. So being in a relationship with someone like that isn't hard after you get past their shell! They will only be like that with others, therefore, nothing from there should affect you being in a relationship with them.

He has selective mutism.