My boy, who is now 14, showed similar leanings.  He’s been primarily a lefty.  Would switch to right when he got halfway across a page or tired.  My parents are both left-handed, but I’m right-handed.  My son’s handwriting has been lovely for years and he has both art and science leanings at school.  All I can say is to encourage the ambidexterity.  Love to you and EM.