I think it's an error done by the academics related to the "average" sample of Medieval Tuscans.
When I ran the "average" medieval Tuscany as a sample source versus Swedes and Imperial Tuscany. I got 19% Swedish.
I have 5 samples out of 9.
[TH="class: singleheader, colspan: 2, align: left"]Target: Italy_Medieval_Chiusi_East_Med_Profile:ETR014
Distance: 5.8434% / 0.05843383[/TH]
[TD="class: singleleftcolumn, align: right"]100.0[/TD]
[TD="class: singlerightcolumn"]ITA_Etruria_Imperial[/TD]
[TD="class: barchartmode1 nonselectable, colspan: 2"][/TD]
[TH="class: singleheader, colspan: 2, align: left"]Target: Italy_Medieval_Chiusi_Central_Italian_Profile:ETR013
Distance: 4.2658% / 0.04265800[/TH]
[TD="class: singleleftcolumn, align: right"]97.8[/TD]
[TD="class: singlerightcolumn"]ITA_Etruria_Imperial[/TD]
[TD="class: barchartmode1 nonselectable, colspan: 2"][/TD]
[TD="class: singleleftcolumn, align: right"]2.2[/TD]
[TD="class: singlerightcolumn"]SWE_IA[/TD]
[TD="class: barchartmode1 nonselectable, colspan: 2"][/TD]
[TH="class: singleheader, colspan: 2, align: left"]Target: Italy_Medieval_Chiusi_Central_Italian_Profile:ETR010
Distance: 4.1774% / 0.04177429[/TH]
[TD="class: singleleftcolumn, align: right"]94.0[/TD]
[TD="class: singlerightcolumn"]ITA_Etruria_Imperial[/TD]
[TD="class: barchartmode1 nonselectable, colspan: 2"][/TD]
[TD="class: singleleftcolumn, align: right"]6.0[/TD]
[TD="class: singlerightcolumn"]SWE_IA[/TD]
[TD="class: barchartmode1 nonselectable, colspan: 2"][/TD]
[TH="class: singleheader, colspan: 2, align: left"]Target: Italy_Medieval_Chiusi_Central_Italian_Profile:ETR007
Distance: 3.9967% / 0.03996698[/TH]
[TD="class: singleleftcolumn, align: right"]76.6[/TD]
[TD="class: singlerightcolumn"]ITA_Etruria_Imperial[/TD]
[TD="class: barchartmode1 nonselectable, colspan: 2"][/TD]
[TD="class: singleleftcolumn, align: right"]23.4[/TD]
[TD="class: singlerightcolumn"]SWE_IA[/TD]
[TD="class: barchartmode1 nonselectable, colspan: 2"][/TD]
[TH="class: singleheader, colspan: 2, align: left"]Target: Italy_Medieval_Chiusi_Central_Italian_Profile:ETR003
Distance: 3.7818% / 0.03781795[/TH]
[TD="class: singleleftcolumn, align: right"]90.4[/TD]
[TD="class: singlerightcolumn"]ITA_Etruria_Imperial[/TD]
[TD="class: barchartmode1 nonselectable, colspan: 2"][/TD]
[TD="class: singleleftcolumn, align: right"]9.6[/TD]
[TD="class: singlerightcolumn"]SWE_IA[/TD]
As we see 1 East-Med Medieval Tuscan cannot be modeled, he comes as fully Imperial Tuscan. It's also obvious on the PCA if you add Germanic the average Imperial it only becomes more distant from that particular sample. The one that plots more northern probably scores 20%, as for those in the Middle vary from 2.2% to 9.6% as seen in G25. I suppose if you remove the 2 outliers you will get a one digit percentage. The fit is not tight though
(If you use Pre-Roman Etruscan vs Imperial Tuscan vs Iron Age Swede, you loose nearly all the Germanic and get a better fit.)