[XeTeX] Problem with leading with Charis SIL or Doulos SIL

[Lammert, Richard A.]

I seem to be doing something wrong to get specified leading with Charis
SIL and Doulos SIL (I am quite a novice with TeX, so I am undoubtedly
missing something--please let me know).

I have used the following definitions in the preamble to set up 14 point
leading:

\newcommand{\basetext}{\fontspec{Gentium}\fontsize{12}{14pt}\selectfont}
\newcommand{\basetwo}{\fontspec{Charis
SIL}\fontsize{12}{14pt}\selectfont}
\newcommand{\basethree}{\fontspec{Doulos
SIL}\fontsize{12}{14pt}\selectfont}

However, only the Gentium comes out with 14 point leading; Charis SIL
comes out at about 20 point and Doulos SIL comes out at about 19 point.
It seems to me that the specified "\fontsize" should give all the same
leading.

Vital specs: XeTeX 0.99b; fontspec 1.9; TeXShop 2.09a; Gentium 1.02;
Charis SIL 4.0.02.r1; Doulos SIL 4.0.14.r1; Mac OS X 10.4.5.

Richard Lammert