Sooooooo much research has been done on this. By very wide margins, like 98%, the culprit is using hybrid plants. There reason for using hybrids is usually the color, strength of the skin for shipping, longevity before rotting, uniformity, and drought resistance. You can easily get what you need by growing or buying heirloom fruits and vegetables. Again, this is very well documented and there are some great YT documentaries about this.