Dr Jennifer Ashton had reason to celebrate on Wednesday as she marked a very special occasion close to her heart.MORE: Dr Jennifer Ashton looks incredible in bikini during family vacationThe Good Morning America star was feeling nostalgic as her son Alex turned 23, and his birthday didn't go without mention on social media.Jennifer paid a heartfelt tribute to her son on his big day, alongside a series of family photos, including one of her and Alex at the beach, and another of them and daughter