I was watching this television show about how forensic investigators used the style of writing from some notes left with a victim to find a suspect and eventually bring him to justice. It is true that each of us have certain writing style, very unique to ourselves. These guys used the usage of abbreviations, composition, active/passive sentences, use of adjacent, nouns, fractions, brackets, capitals, hyphens, punctuation, etc. to compare and eventually find their man. This would obviously apply even more to someone with certain volume of writing or perhaps a book out there and makes it easy for the experts, as well as curious amateurs to guess/find the actual writer, even if pseudonyms are used or there's no other identification marks.
On a different unrelated note, one of the regular readers wanted me to pass along this information; She apparently has done her homework and discovered that according to the web site for Publisher's Clearance House, the country of Botswana is in desperate need of some democracy, so she has taken it up to write them a new constitution, choose suitable future presidents, members of parliament and heads of judiciary, armed forces and security police. After all, she is a software engineer from Palo Alto which makes her perfectly qualified to offer her expertise in such matters. If you are interested to know more and can read Setswana, contact me and I'll forward your information to her. She is also available on private consulting basis for a nominal fee, so if you are from one of the desperate backwards third world countries in need, let me know. She'll even bring her own Coke as well as Pepsi bottles.