Ron:The pronoun problem is worse than you might think. E.g., even if the problem said "... each a product of its regional influences", it would still be wrong.
"Regional influences" are vague forces—basically, like the culinary culture of an entire geographical area. These forces don't emanate from, or belong to, any particular person or thing, so it's impossible for any construction of the form "its/their/____'s influences" to make sense here.
我听到了 多大的数算大数?你“他妈”70、80都不算大,哈哈哈,减压~~