[1] She was raised in Sunnyvale, California by her parents Armand and Mabel LeSiege; amid her father's early death, her stepfather Raymond Phelps helped out.

[2] Although a bassoonist in her youth, LeSiege attended San Jose State University (SJSU) to study French horn, graduating in 1968.

[3] Among her students was the composer Clare Shore,[6] who recalled her teacher's encouragement in studying works of contemporary classical music, particularly Samuel Barber.

[2] Amid a brain cancer diagnosis in 2009, LeSiege retired from full-time teaching and moved to Rockland, Maine.

[2] In an obituary, the former-student and singer Adria Firestone described her as a "gadfly with feet-on-the-ground playfulness and discipline infused with passion"[9] Soprano Teresa Radomski, a fellow Eastman student, emphasized the beauty and skilled prosody of LeSiege's music, describing her as "a wonderful teacher, warm, compassionate and kind".

[3] Her personal mood and the source material would determine her approach to individual compositions and she described music as "controlling the existing energy into sound".