Some People Say That Marrows Are Fruit, Other Vegetables. Who Is Right?

Strictly speaking marrows can be classed as both fruit and vegetables.  They are regarded as vegetables because they are a plant which is cooked and eaten as part of the main course, not a dessert.  They are also vegetables in the sense of animal, vegetable or mineral ie they are not animal or mineral, so it can be assumed they are vegetable.
However, marrows can also be classified as fruit.  Botanists use the word to mean the parts of a plant which contain its seeds.  By that definition a marrow is a fruit.  Also falling within this category, as you may expect are apples and oranges etc.  But tomatoes also are classed as fruit, as is corn on the cob and even the runner bean!
Interestingly, rhubarb which forms the basis of many a jam and crumble is actually classified as vegetable because we do not eat its seeds, only the flesh.