You are responsible for professional growth of your team. Whereas family, you accept them unconditionally.
You must give constructive feedback to your team. Whereas you love your family despite their flaws.
You may perhaps have to even fire a team member and bring a new one, if they are not growing. If you treat them as a family, you deny them the growth they deserve because you are now bound to keep them happy. Not a good thing either for your team nor for you.
The best thing you could do to your team’s growth, is not treat them like family.