Why PCA sometimes give strange positions ?

[Ahaddad]

Im very curious to know why some PCA of G25 give strange points, for example son is not the same line of parents and not same distance too, other thing is my friend mother is Galician Spanish, in map of Eurasia she fit close of Albanian,Moldavian or Macedonia Greek but she is not. In Europe map she fit close of Spain and Portugal.

griseldaScaled,0.093336,0.131002,0.012445,-0.000323,0.026774,-0.001673,-0.009165,-0.009923,0.01718,0.019135,-0.011204,0,-0.011596,0.002615,0.020493,-0.01021,-0.031162,0.002028,-0.000629,-0.003876,0.000375,0.013848,0.008505,-0.004338,-0.008263

griselda,0.0082,0.0129,0.0033,-1E-04,0.0087,-0.0006,-0.0039,-0.0043,0.0084,0.0105,-0.0069,0,-0.0078,0.0019,0.0151,-0.0077,-0.0239,0.0016,-0.0005,-0.0031,0.0003,0.0112,0.0069,-0.0036,-0.0069

[JamesBond007]

I have personally given up on G25's modern populations. Davidski is supposed to be phasing it out. Davidski says to model your modern ancestry using Iron Age and medeival samples. It has me as Central Dutch which can't be true. Some English people are closer to the Dutch or Danes than the average , though. The English are Germanic-celtic mutts so I model myself thusly :

Target: KevinG_scaled
Distance: 1.9624% / 0.01962356
42.8 England_IA (England Iron Age )
32.0 ISL_Viking_Age_Pre_Christian (teutonic scandinavian invader)
25.2 SVK_Poprad_MA (teutonic continental invader)

This shows that it is the West midlands since Welsh is number 2 :

Distance to: Kevin
2.37520525 English_Midlands
2.65992481 Welsh
2.70270235 English_North
2.81662919 England
2.88652040 Dutch

http://vahaduo.genetics.ovh/k15-vahaduo.htm


Basically, it is a convoluted and sophisticated process to find out the truth with this stuff.