ἴουλος, in ancient Greek, has several more meanings than "downy-bearded." It means "corn sheaf," and is the title of a song honoring Demeter.It also means "catkin," which are fuzzy flowering structures of willow, hazel, and hornbeam trees. Source: http://perseus.uchicago.edu/cgi-bin/philologic/getobject.pl?c.35:3:199.LSJ
If I understand Latin suffixes correctly, |-ius| makes its meaning "SON OF |Julus| Downy [-bearded], *"not just "Downy[-bearded]" alone.*"Downy-bearded" is like our idiom "peach fuzz." Often translated as "youthful," "baby-faced" is closer to its original intent. Since women don't have beards, this root is patently masculine. Feminine suffixes show a relationship to a male JULUS (JULia) or his descendants, such as JULIUS (JULIana), as do masculine suffixes (JULius, JULIan[us]).