I believe the factors that affect someone’s intelligence are firstly what they already are within – it is who they are in spirit, and then of course it is their DNA, and then environmental factors, such as nourishment – what is nurtured/nourished/encouraged in them. So it is a combination of all three, and certainly spiritual practices can develop intelligence if it is already there, and it is able to be enhanced by clearing yourself of debris, and also attuning to source, and if you consciously ask to increase your intelligence it will be done.