Answer:
It is difficult to diagnose a skin condition without seeing it, but based on the description provided, it is possible that you and your sister have a common genetic condition called keratosis pilaris. Keratosis pilaris causes small, rough bumps on the skin, particularly on the arms, thighs, and buttocks. The bumps are usually skin-colored, and they can be itchy or irritated.
Keratosis pilaris is a benign condition that is not caused by diet, but rather by an overproduction of keratin, a protein that helps protect the skin. The condition tends to run in families, so it is likely that your parents passed on the gene that causes it to you and your sister.
There is no cure for keratosis pilaris, but it can be managed with regular exfoliation and moisturizing. You may also want to avoid hot showers and harsh soaps, which can dry out the skin and make the condition worse. Over-the-counter creams containing urea or lactic acid may also help to smooth the skin. However, it is important to consult a dermatologist for an accurate diagnosis and treatment recommendations.
Hope this helps!