A “Happy Birthday” chorus lilted through the gallery as a 2-year-old was feted by fellow class participants, including twins who declared that they were “old and big” (in a program for children 18 months to 4 years). A newly minted big sister returned with her mom and shared news of her little brother’s arrival. And the following day, the Woodson Art Museum welcomed the youngest Art Babies participant in recent memory . . . a 3-week-old cherub snuggled close to a proud, elated, sleep-deprived first-time-mom.