family line

NOUN
11 LETTERS · STARTS WITH F

family line is a valid 11-letter word worth 18 points in Scrabble and 21 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
F4A1M3I1L1Y4L1I1N1E1
4 + 1 + 3 + 1 + 1 + 4 + 0 + 1 + 1 + 1 + 1 =18 PTS
DOUBLE WORD → 36TRIPLE WORD → 54
MEANING

What does family line mean?