Question regarding the r2g/tf2g importance scores

[psl-schaefer]

If I understand the GENIE3/GRNboost algorithms correctly, we first we first normalize the variance per target to 1, such that the importance scores per target sum up to 1 (given that the prediction is almost perfect) which facilitates the comparison of importances score for different target genes.

Why do the importances scores per gene sum up to 1 in the region-gene data frame, but not in the tf-gene data frame?

This is for example how the sum of importances scores per gene looks like