Lightbulbing Techs: How you know

[Water2Funk]

Does anyone know what tech triggers a Great Person to lightbulb a certain other tech? For example, I tried beelining/lightbulbing to liberalism, by lightbulbing CS with a GS, but instead I moused over the icon and was prompted to instantly research "Optics" instead!
Does anyone know how to control what tech a great person will lightbulb, preferably with Scientists, Engineers, Artists, and Prophets after Divine Right?

 

[UncleJJ]

This article Great People Tech Preferences by DaveMcW gives a full explanation of which tech each type of GP will lightbulb. Basically they will only offer one tech and that is taken from a list. Which tech they offer can be manipulated by researching and or trading for other techs in a particular order.