How do I set a preferred email address to sent to?

Using Mac Mail on a MacBook Air or iPhone, how do I set a default email to send to? I routinely send emails to one of my contacts that has both home and business email addresses? When I start typing the name, I am greeted with the business email and then an option to follow an arrow to choose the home address. No matter how many times I choose the home address, it continues to default to the business address. How can I make it default to the home address? Thank you