Hm.. time to get creative! So, Ghetsis' parents were the leaders of a cult, (his parents had split to form their own evil team from the original group of Giovanni, Maxie, Archie, Cyrus and them let's say) not a super creepy one, but one where there was a monarchy etc. This cult looked down on pokemon as only animals, and people as their masters. This cult soon disbanded however, but it had entranced Ghetsis' young soul. He wished to achieve ultimate power like his parents of the cult, but knew he couldn't go about it in the same way, as the most people of the Pokemon World love pokemon too much and see them as people. He needed a way to take away his adversaries stance that pokemon and people are equal and friends. Around this time Ghetsis inherited a vast sum of money from his dead parents who died in a rock slide while traveling to Opelucid via victory road from their large home on the top of Victory Road. (they as the leaders of the cult were quite wealthy) He felt this disturbance from his home, and raced down to check it out. After determining his parents were dead, he saw an injured deino nearby. At this time, deinos were very rare, and not many people knew what they looked like. He also noticed it had many bites and bruises covering it (as we know, They cannot see, so they tackle and bite to learn about their surroundings. Their bodies are covered in wounds.) And then it dawned on Ghetsis. He could use this deino and show people how it had been "abused," and that everyone should release their pokemon to stop this enslavement/abuse. Those worthy could join him. Soon this group became a team, with a hierarchy. (that's why ghetsis' robes look like a castle/the seven stages, he emulated his parents' cult) They needed to find a king though...
And wow I got offtrack. But yeah he was brought up strictly and with an air of superiority concerning pokemon. By his parents in the cult. Lol