Joyce’s parents are a bit older than the other characters’ parents. Joyce is the youngest of four siblings, while the rest of the cast are mostly first or second in birth order, so I get to gray and wrinkle up the Browns a bit more. They’re likely pretty close to the age of my own parents.
You can probably see in them the general design philosophy of how I draw parents. They’re almost patient zero for that, being designed second only after Danny’s parents some time in 1998. Mr. Brown gets Joyce’s eyes and headshape and Mrs. Brown gets Joyce’s nose and slightly shorter version of her daughter’s hair (and a more round physique that Joyce is likely to take on as she gets on in years). I always find it helps to give the most distinctive physical characteristics to the opposite-sexed parent and then throw all the other features at the other parent — and few characteristics are more distinctive than Joyce’s big blue eyes. I don’t want moms to always look like aged-up daughters and dads to always look like aged-up sons. They can be sometimes, though, for lulz.