There are set courses by God,kind of like an instinct for us,but since we have a choice to make decisions,we can choose not to follow that course although it is in us.
The Bible says that creation testifies there is a God,so they are without excuse.
It will be an instinct in us to believe there is a higher power when we observe creation,but people later on in life choose not to believe that.
The Bible says that a man should have short hair because he is in the image of God,and even nature teaches that it is a shame for a man to have long hair.
When the 1960's came and the youth were saying have your way,rebel against authority,they grew their hair long.
The Bible says that God made man upright,to do good,but they sought out many inventions,their own ways.
There are set courses,like an instinct to us,but we have a choice to not choose that,and if we choose to go against those set courses that God instilled in us,it is wrong.
God made a man and a woman to have a natural attraction to each other,that is what is instilled in us,a set course by God,because God wants a man and a woman to be together,so to go against that set course would be to sin,for it is like an instinct to us.We would be going against the thing that our instinct is telling us not to do.
Also homosexuality is lust of the flesh,and is therefore sin.
The Bible says creation testifies there is a God,so they are without excuse,but when they knew God,they did not want to believe there was a God,but wanted to believe things came about in another fashion,like evolution,or the occult,that are nature worshippers.
After they continued on in that mind set,God giving them time to repent and acknowledge truth,when they did not change,God gave them over to a reprobate mind,which means God stopped working with them,and all they seen is the fleshy ways,which in the flesh dwells no good thing.
They became filled with all unrighteousness because the flesh will always be in rebellion against the Spirit,and all they could see is the flesh,and one of the things included in that unrighteousness is homosexuality,which shows that homosexuality is a fleshy pleasure,lust of the flesh,and sin.
It is an instinct in us for a man to have a natural attraction for a woman,and a woman to have a natural attraction to a man,and to become homosexual,is to go against yourself for the instinct is in you,and to go against God,for it is lust of the flesh.
So to be homosexual,not only do you sin against God,but you sin against yourself.