I do have been planting papayas in my garden for the past 20 yrs. I have had this case of papayas without or very less than normal seeds. But this is an isolated case. Lately I have had the opposite problem. All the papayas I plant from store bought fruit, yield fruits with a huge amount of seeds. The taste of these fruits is different from original store bought but this is explainable due to cross pollination.
If all the papayas give less seeds and mine give abnorbmally more, there should be a factor which is responsible for number of seeds.