People have different propensities.
Each propensity or tendency belongs to a wide spectrum. Here are some of these spectra:
Feverish temperament, constantly vexed, at one end. Calm disposition, showing little anger once in a blue moon, at the other end.
A sensualist, never satisfied by the pursuit of pleasures, at one end. Pure-heart with no craving, even for the barest necessities, at the other end.
Greedy, unsatisfied even with the biggest fortune, at the one end. Feeling content even with the insufficient little that he has, at the other end.
One who will go hungry in his hoarding efforts and suffer terribly when spending a penny of his own, at one end -- one who wastes all his money knowingly and of his own volition, at the other end.
Optimist -- Pessimist
Miser -- Philanthropist
Cruel -- Merciful
Coward -- Stout-hearted
And so on
The origin of each propensity
There are generally three levels of influence that shape the individual's propensities:
The surrounding environment propels the person to acquire propensities that are promoted by that environment.
The parents' essential character traits and their conduct during the AoM (when the child is conceived) shape and orient their child's dispositions. These will be more innate than those acquired from the environment.
Reincarnation of the person's soul, the "background" of the soul, determines its character at the present lifetime.
Attraction to the same sex comes about through any or all of these factors.
No one is born perfect
No human is born with perfect propensities, regardless of which propensities he possesses, which family he was born into, or what environment he was raised in. There are always character challenges that need work.
But why are we created imperfect?
So that by mending those ill-propensities with our own efforts, we will become partners with G-d in His creation.
Which propensities to refine and how
G-d's Commandments were given to refine humanity. To push us into shape, specifically in common "pressure points".
Just like pressure points hurt when force is applied, so too it is uncomfortable to change our ill-tendencies.
Different commandments are challenging for different people, depending on their personal inclinations.
The Seven Noahide Laws, for example, are applicable to all humanity. They are seven general pressure points, areas that humanity need to work on.
NOTES AND REFERENCES
Spectrum of propensities. Rambam, Deot, 6
The surrounding environment impacts the propensities of people. Ibid
The parents' essential character traits and their conduct during the AoM of conception shape and orient their child's dispositions. Tanya Ch. 2
Previous reincarnation sets up the character of the next reincarnation of the same soul. Specifically for LGBT – Responsa Nezer Cohen Pt. 1 Ch. 5 p.210a. Ramak and Gra...
Attraction to the same sex comes from the conduct of the parents during the AoM (of conception) . The Talmud says (Nedarim 20a) "Why are people born lame? Because the father turned his table over".
"Turning his table over" is an analogy comparing the AoM to the act of eating. There are three opinions as to what this analogy actually corresponds to:
Through the anus, that is, "שלא כדרכה" – "not the normal way for her". Responsa of Panim Meirot II 158.
From the back: Rashi, ראב״ד in Shaar Hakdusha, רשב״ץ Magen Avot 3;4, ספר חרדים p64, של״ה Shaar Haotiot Kdushat Hazivug 363.
She is above and he is below: Rashi (second comment), מרדכי Nida 732).
The Commentators (Rabbenu Asher (רא״ש), Rabbenu Nissim (ר״ן), and Tosafot) clarify the connection between turning his table over and the consequence of lame children: Turning his table over is an immodest change associated with the thigh, hence that impacts the thigh of the child.
The Zohar (Tikun 70, p.133) implies that "turning his table over" (has another consequence; it) causes his male son to behave like a woman...
The connection between lameness and homosexuality seems to be another meaning of thigh: The sexual organ (similar to "יוצאי ירכו" – the offsprings of a person, also known by "the third leg"). Because the change was to do with that thigh (wrong place / wrong position), it impacts the sexual orientation of the child. Also note the three interpretations of "turning his table over" are all associated with the manner of SSM. Also see Responsa of נחפה בכסף (Even Haezer 42c) that the lust of AoM in an abnormal way is to do with the lust for SSM.
Previous incarnation cause attraction to the same sex. As a result of the soul in a previous reincarnation either (1) participating in SSM for extra fun (despite being heterosexual), or (2) excessively engrossed in AoM (in a heterosexual way). Being born as LGBT is measure-for-measure for either, requiring the soul to fix the previous incarnation by (1) staying away from SSM despite now naturally craving it, and (2) engaging in the AoM (with his wife) but without physical enjoyment.
By mending our ill-propensities we become partners in Creation with G-d. Midrash Bereshit Raba 11:6. Yalkut Shimoni Genesis 1:5.