My children are 17 and 19 and I still want to hold their hands walking across a mall parking lot. (Yes, they think I'm nuts.)
Mine are 21 and 18 yr old twins and I do the same thing often - makes them realy mad but old habits are hard to break.
I can relate. No matter which of my children (now adults)is in the passenger seat with me, if there's a sudden stop they get the right arm across the chest. They just laugh about it.
(Yes, they think I'm nuts.)
Mine thinks I'm nuts too. I've been trying unsuccessfully to get her to keep the covers on for 19 years now!
Now that you mention it; I remember in the times before it was mandatory to buckle small kids (not little babies) in child seats, or putting them in the back seat only. I always had a habit of putting my arm out in front of them, as if to hold them back in their seat! I would do this in order to keep them from falling forward into the dashboard if I had to stop fast.
And you know what? I still catch myself doing this occasionally, in spite of myself! My kids laugh when I do that, but occasionally, it's an unconscious act!