Yeah good point. No citizenship by birth here.
http://www.ica.gov.sg/page.aspx?pageid=132&secid=130
Conditions to apply for Citizenship:
Person who is at least 21 years of age and has been a Singapore Permanent Resident (SPR) for at least 2 to 6 years prior to the date of application. Applicant who wishes to apply under his/her own merits may come for a preliminary assessment interview after 1 year of permanent residence.
SPR who has satisfactorily completed full-time National Service (NS).
Spouse of Singapore Citizen with a minimum of 2-year SPR and married for at least 2 years preceding the date of application.
Minor born outside Singapore but is residing permanently in Singapore, and whose parents are Singapore Citizens.
Child born outside Singapore whose parent is a Singapore citizen.