Second, “The combination of these two things that I lack” is overly complicated. Have you considered “The lack of these two things have combined to open the doors to…”

Third “opened the doors to reading” sounds funny to me, but I can’t figure out why. You might be able to depending on the context, but maybe you could drop reading entirely. Also genres are already types. “Types of Genres” is redundant.

“The lack of these two things have combined to open the doors to different genres, mainly fantasy fiction.”

Or if you need the “reading” part in there:

“The lack of these two things have combined to open the doors to the reading of different genres, mainly fantasy fiction.”

“genres” = “types”

“these two things” should be spelled out (unless you did in the preceeding sentence)

The combination of x and y, which I lack, consequently opened the doors to reading different genres, mainly science fiction.

“consequently” means “caused”, so your lack caused you to read other types of literature – strictly speaking, your perception that you were lacking in a couple of areas, coupled with your further perception that this was a short-coming which should be overcome, spurred you to following other literary pursuits.

Perhaps a better rewrite would be a complete reformulation: “Feeling hampered in my efforts by my lack of breadth in a couple of areas, I embarked on a plan to read other genres, especially science fiction.”.

Here’s MY revision–but to repeat, I don’t know what went before this sentence.

“Because of these two things that I lack, I have been inspired to read a variety of genres of literature, mainly fantasy fiction but also…” (It would be better to include another genre, such as sci fi or mysteries or romances.)

The word “things” could use a synonym–but again, I don’t know what you wrote before. SKILLS would be a good word if it fits. “Because of these two skills that I formerly lacked….”