Expression for Type members results in different Expressions (MemberExpression, UnaryExpression)

The reason this happens is that Age is a value type. In order to coerce an expression returning a value type into Func<Person,object> the compiler needs to insert a Convert(expr, typeof(object)), a UnaryExpression.

For strings and other reference types, however, there is no need to box, so a “straight” member expression is returned.

If you would like to get to the MemberExpression inside the UnaryExpression, you can get its operand:

private static MemberExpression GetMemberExpression<T>(
    Expression<Func<T,object>> exp
) {
    var member = exp.Body as MemberExpression;
    var unary = exp.Body as UnaryExpression;
    return member ?? (unary != null ? unary.Operand as MemberExpression : null);
}