You'll get a lot of misguided advice on an app like this. At the early days of a startup you need people who care, who will find a way to succeed despite the odds, who will stick around even if it doesn't make economic sense for them. Friends, family are often some of the best people to work with. (if, its an important if, if they are excellent)

I would only be upset about this if people who have a personal relationship are held to a lower bar. The bar should be higher for them to avoid any doubt about favoritism.

In your case the real question is not their personal relationship, its more about if the team is excellent and if you trust them.