Why Aegon may not really be Aegon Targaryen

[Tyrion's Wife]

In the book 'A Dance with Dragons', Aegon Targaryen is described as having lighter purple eyes than Targaryen and Targaryen blond hair, which he dyes purple to hide his identity. 

Rheanys, his sister, on the other hand looked like a Martell, with olive skin and dark hair.

Although theoretically it is possible for Aegon to look like his father, isn't it more likely for him to look like his mother?  Even Jon Snow, who has now been practically confirmed to be his son, looks like his mother Lyanna (there's a passage in the first book describing Jon's appearance from Catelyn's perspective, about how he had the Stark looks more than Eddard's  trueborn children did).

So maybe, this can be some evidence that Aegon may not be who Varys and Iliryo say he is, even though he himself may not know this.  What are your thoughts about this?

[Jon Snow Nothing]

Aegon might be fake but the child that was presented as Aegon, smashed head and all, had silver hair.

Viserys had light purple eyes. Dany is said to have violet eyes (darker) and Rhaegar sometimes are mentioned to have indigo eyes, even darker.

People believe this Aegon is a Blackfyre, the "mummer's dragon" Dany is told by Quaithe.

[The Fattest Leech]

All first born children of a Targ to non-Targ parent always look like their non-Targ parent while having the personality of the Targ parent. A clever way to disguise certain children. 

The second child almost always look like a Targaryen, while the subsequent children can vary. 

There is one case where it was reversed and that was a case of identity issues within the Dance of Dragons. 

You can read about it here if you want to. You can read about it here