Now, Modern science (e.g. Biological anthropology, Evolutionary psychology, and Human Biology etc) maintains that individuals are both genetically and environmentally predisposed to believe, or not to believe certain doctrines.
One could make a case that Scripture supports the idea that what a person is like is affected by their genes and environment. The conclusions of "fields of study" don't mean much to me, because they usually are based on assumptions and are always incomplete. (What field of study is "done" and has no further research to do? It is hubris to consider us to finally know the truth just the same as it was when people did it millennia or 150 or years ago.)
Therefore, some people would innately stand a better chance than others to believe, or not to believe the Gospel of Jesus Christ, based on the aforementioned.
You suggest that there is randomness and chance involved, but that is contrary to your following text about God's sovereignty. Chance and probabilities are real from a human perspective, they are not from God's perspective.
However, we also know that God is the ultimate cause behind the genetic and environmental factors which would predispose people to believe, or not to believe the Gospel of Jesus Christ. John 1:3
No, we do not know that. What we know is that Scripture demonstrates from cover to cover that we are the product of both God's decisions and human decisions.
How, then, can they call on the one they have not believed in? And how can they believe in the one of whom they have not heard? And how can they hear without someone preaching to them? (Romans 10:14, 1984 NIV)
This implies that God never created people equally in terms of their chances to be saved, or not to be saved. As we know that some people would always stand a better chance than others to be saved, or not to be saved.
This is good, and pleases God our Savior, who wants all men to be saved and to come to a knowledge of the truth. (1 Timothy 2:3-4, 1984 NIV)
[about Jesus]
... who gave himself as a ransom for all men—the testimony given in its proper time. (1 Timothy 2:6, 1984 NIV)
For there is no difference between Jew and Gentile—the same Lord is Lord of all and richly blesses
all who call on him, for,
“Everyone who calls on the name of the Lord will be saved.” (Romans 10:12-13, 1984 NIV)
Its fine if you want to examine the predisposition of people to salvation, however, it must include the fact that it is available to everyone.
Thus, God is the Great Architect of Inequality in regards to the Ontology of Salvation; since he never created individuals to be exactly identical in terms of their genetic makeup, nor identical in terms of their social environment. John 1:3, 6:44, 6:65
Perhaps you have forgotten that no one deserves to be saved, and God would be 100% morally good even if he did not save anyone. The inequality that exists is the results of the decisions of humans.
For God does not show favoritism. (Romans 2:11, 1984 NIV)
Since individuals would always differ in terms of their genes and their social environment it means that some people would always have a better chance than others to be saved, or not to be saved.
The degree to which people have difference "chances" is the result of human decisions, not God's.
If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it.” (Genesis 4:7, 1984 NIV)
Thus, we know that human societies were never meant to be a level playing field in terms of the Ontology of Salvation; since individual differences would always entail some people having a better chance than others to be saved, or not to be saved.
Yes, ancient humans (as well as near ancestors) decided to reject God in different ways and at different times. It is they who are responsible for how we differ in our rejection of God.
Thus, some people would always have a better chance than others to be saved, or not to be saved; which implies that God has elected only few people to enter the Kingdom of heaven (Matthew 25:34), whereas the rest of humankind have been elected for the purpose of destruction (Revelation 13:8); and God decided this long before the world was created (John 6:44, 65).
Discuss.
You are mixing human perspective with God's sovereign perspective, which leads to reasoning that will result in incorrect conclusions. Keep in mind that God will not reward or punish people for things they never did. We are responsible for our decisions, actions, and consequences of our actions.
“Yet your countrymen say, ‘The way of the Lord is not just.’ But it is their way that is not just. If a righteous man turns from his righteousness and does evil, he will die for it. And if a wicked man turns away from his wickedness and does what is just and right, he will live by doing so. (Ezekiel 33:17-19, 1984 NIV)