While my younger brother famously walked at 9 months, my own son hit that milestone at a ripe 16 months. I looked longingly at infants who waved on demand, and even blew kisses, until suddenly, unprompted, a few months short of his second birthday, my son flapped his pudgy hands and said brightly: "Bye-bye."

Milestones like these can be a helpful way for parents and experts to gauge whether a child is developing normally — physically, verbally or socially. But for many parents in today's hyper-competitive and hyper-vigilant parenting environment, having a baby who rolls over at 2 months affords coveted bragging rights, while having a baby who doesn't induces anxious Internet searches.

"It is something that all parents struggle with. It's hard to avoid it, the comparisons," said Claire Lerner, a child development specialist with Zero to Three, a nonprofit organization focused on early development.

But Lerner added that there is a wide variation for when kids achieve the classic baby and toddler milestones.

"What's important is you're seeing them make forward progress. If your child isn't crawling yet but she has started rolling to reach her toys, that is progress," Lerner pointed out. "If your child is sort of stagnant and not making forward progress, that to me is the thing to watch for."

But Lerner agrees that it is worth checking with an expert because parental anxiety can actually stymie a child's progress. Children pick up on the feeling and can feel frustrated at themselves, resentful about the pressure, or discouraged from trying because the situation has gotten so stressful.

Kristine Watson of Austin, Texas, used to be one of those constantly worried moms. She would feel fine about her son's progress until they went to a baby class, where she would be barraged by questions about what he could and could not do, followed by hints that she should get him checked out.

"Every kid was given some kind of diagnosis if they didn't fit into this exact mold," Watson says. "It does make you paranoid that there is something wrong when there isn't."

When her son turned 3, she realized he was perfectly fine, and she stopped tracking everything: "I spent so much time looking at him and analyzing him instead of enjoying him."

"I feel like it all sort of evens out in the end," Watson added. Her son turned out to be a pro at swimming.

Indeed, my little guy may be a little slower out of the gate, but he catches up pretty quickly. At 21 months, he is a master Lego builder and can count to 10, almost perfectly, in both Arabic and English.