I suppose this is already a work in progress, since some pages within geni.com are displayed correctly in mobile devices.
However, the main site of the web (http://geni.com/home/index) is still displayed in desktop mode in mobile devices, making the text size so small that it's non-legible.
Also, while the tree view itself works in mobile devices, its layout is not optimized due to the lack of horizontal space in the screen. A vertical layout featuring narrower people boxes would be easier to browse, as mentioned here: https://help.geni.com/hc/en-us/community/posts/5175058184983-Vertical-boxes-in-tree-display-like-in-the-flash-version
Part of this was already discussed in this thread:
https://www.geni.com/discussions/134150