Affection is a feeling of care or tenderness for someone or something. If you have a propensity to choose something, you have an affection for it.
Ex: Although he tried to hide it, it was obvious that the town's biggest curmudgeon now had an affection for the sound of children singing as they passed his window on their way home from school.
Ex: It was with great affection for his long-time colleagues that the writer composed his final words to be delivered at the retirement party.
If you are affectionate, you show a liking for someone or show care for someone. To be affectionate is to demonstrate your feelings about a person or thing.
Ex: Some people are more affectionate than others. My brother for instance is quite shy about public displays of affection.
Ex: The librarian was pleasantly surprised by the affectionate children's hugs and cries of joy when she returned to storytime after a lengthy illness.
A penchant is a tendency to choose something or a strong liking for something, such as a type of literature, food, or music.
Ex: Michael has a penchant for scary films, so he often finds himself in search of friends who want to go with him to see the latest horror film.
Ex: My penchant for biographies has led me to read about a variety of historical personages, from Florence Nightingale to Mark Twain.
If you do not have a penchant for something, but grow to like it, it can be said to be an acquired taste. An acquired taste is something that one may not like on the first try, but develops over time and exposure.
Ex: For me, olives have always been a favorite, but for my husband, they were more of an acquired taste.
Ex: For many people, heavy cabernets are an acquired taste, something that they learn to drink after starting with lighter table wines.