adoption

My fiancé and I really want to adopt in the future. We have been talking about it and we know that it feels right... We want to try and have one and then adopt. I told my dad and grandparents today and they acted like it was not a good idea. They kept saying "Why would you do that? Don't you want your own?" And it hurt. Like yes we want our own but we know it feels right to adopt! Any thoughts on how to handle people and their negative reactions?:)