lower case ‘g’ is not conclusive in and pf itself.
[anedcdotal] My handwriting has changed very little in 40 years.
I have 3 different types of lowercase ‘g’ that depend on situation, energy and efficiency.
I won’t hang my “it’s Obama” hat on the ‘g’ but neither will I hang the “it’s NOT Obama” hat there either.
What is needed is a profressional handwriting expert. They look for all kinds of stuff besides just the shape of the letters. Angle, pressure, etcetc. I also use various forms of upper and lower case letters depending on how formal or not (a letter, or a to do list for myself, etc), in haste or not, and so on.