Drastically different boldness between Latin and Cyrillic encoding of the same font

Question

They want me to typeset English and Russian translations of the same text in the exact same font and style. I loaded UTF8 encoding with babel for Russian and the main font is coming out identical, though the title pages in 60x60 and 40x40 bold font look completely different.

Why and how can the Russian output be produced in the same boldness as English?

English:

\documentclass[12pt,smallroyalvopaper]{memoir}
\usepackage{gentium}
\usepackage{lipsum}

\title{
{\fontsize{60}{60}\selectfont{\textbf{Series Title}}\par}
\vspace*{0.08\textheight}
\fontsize{40}{40}\textbf{Book Title}
\vspace*{0.08\textheight}
}

\begin{document}
\maketitle
\clearpage
\lipsum[1]
\end{document}

Produces:

Russian:

\documentclass[12pt,smallroyalvopaper]{memoir}
\usepackage{gentium}
\usepackage{lipsum}

\usepackage[utf8]{inputenc}
\usepackage[T1,T2A]{fontenc}
\usepackage[main=russian]{babel}
\title{
{\fontsize{60}{60}\selectfont{\textbf{Заголовок серии}}\par}
\vspace*{0.08\textheight}
\fontsize{40}{40}\textbf{Заголовок книги}
\vspace*{0.08\textheight}
}

\begin{document}
\maketitle
\clearpage
\lipsum[1]
\end{document}

Produces: