HI guys

I am seeing too many horror posts regarding BTC being stolen so I am going to protect my coins by a passphrase.
Would 6 names of family members would be secure enough? Because I prefer my passphrase to be memorized.
I realize that 6 names of family members isn't as secure as completely random words but not having to write anything down or store anything has many security benefits too.
My keys are safely stored offline already.

Would 6 random names be safe enough as passhprase against brute force attacks if my private key is known?

Many thanks!