DD1 was around 17mo I think, hard to remember (can't believe our girls are on the downward sprint to 5 btw, went like a blink). I was around 18mo or older myself too when I started walking, Mum's memory also fuzzy but it was a bit after my brother was born. No phyiscal issues but she was/is a small baby/toddler/kid, I had hip issues though and was in a brace for a while. DD1 crawled really early so it felt like forever before she walked, I was an earlyish crawler too.

DD2 had borderline hips that needed periodic monitoring but ended up fine without intervention and was walking by 10months. I was caught off guard.

Surprisingly, they were both around the same weight when the started walking although that's probably just a coincidence. Interesting though.

In the end, both are very physical and big climbers. Not sure why the huge difference in timing other than it is probably becomes more and more irrelevant the further away you get. I always played as many sports as I could fit over the year (basketball, soccer, netball, water polo, swim team and dancing) so maybe all that extra time crawling was good, stacked my coordination lol.