How to query Entity Framework objects where select is a list

I'm attempting to do something easy, but I'm having trouble. With the use of EF6, I have two tables connected by a middle associative table, resulting in a many-to-many relationship:

I want to run a query on every user who is a part of a particular family. I thus receive a variety of families:

var db = new MyProjectEntities(); 
User user = GetUserById((int)HttpContext.Current.Session["CurrentUserId"]);
var families = db.Users.Where(u => u.UserId == user.UserId).First().Families.ToArray();

Then, I want to ask everyone who is a member of these families:

var users = db.Users.Where(u => families.Contains(u.Families));

But I encounter this issue:

Argument for an instance: 'Database.Family[]' cannot be converted to 'System.Linq.IQueryable>'

I appreciate it.