"Traditional Family" typically refers to "as mentioned in the Bible".
Also mentioned in the Bible is the hero King David, slayer of Goliath, and an alleged ancestor of Jesus Christ.
King David had at least eight wives and at least ten concubines who are mentioned in the Bible.
Solomon, in particular, had 700 wives and 300 concubines.
Abraham took Hagar as a secondary wife.
Jacob was married to both Leah and Rachel.
Polygamy was not discouraged until Paul's epistles, written 15-20 years after Jesus' time.
So, which "traditional family" are they referring to?