My son curves his body always to the left when I lift him into the air.....?

My son who just turned one always curves his body to the left when I lift him up above my head when we are playing around. He doesn't seem too be bothered by it but it looks strange that he always does that. He's been doing it as long as I can remember. Also, before he started walking he always crawled with his left leg in front of him and the right leg back. My mom has bad scoliosis so she pointed this out to me as a concern for him, that maybe his spine was curved. He had his one year well baby check yesterday and the doctor said scoliosis doesn't show up that early unless it is so severe that we would definitely know it, but he did say we should keep an eye on it. Has anyone seen this before???