This question is maybe little bit weird and we know if people find you via organic traffic or direct for front page that is great and you have targeted traffic.But somebody can post your website front page on some source where clicks are not natural and then can be lot of artificial clicks on ads. What you think folks?
Yeah, you can place Google Asense ad on your website's front page. Google does not stop you to do that. But you need to place the ad code on internal pages as well so that you can get clicks from various pages and earn money.
Most people's traffic are from the front page of their website. There is no rules against this according to the Adsense FAQ and TOS so it should be fine
You can put adsense code to any part of your site. However your ad placement must comply with Adsense terms of use and publishers guidelines.
There is no explicit rule that forbids you from doing so. In fact, to maximize earnings - it's recommended to put ads on each page where it makes sense (of course, making sure usability and user experience is not impaired; also make sure you are following AdSense's rule for placement, etc).