What courses a one year old baby to have geographic tongue ?

The cause of geographic tongue is unknown, and there's no way to prevent the condition. There may be a link between geographic tongue and psoriasis and between geographic tongue and lichen planus. ref: https://www.mayoclinic.org/diseases-conditions/geographic-tongue/symptoms-causes/syc-20354396

Nothing causes it except the child's genetics. Not anything to worry about, just a trait your child has like a birthmark...