生来・性来|せいらいseirai[1]atamadaka (head-high)

1. adverb, no-adjectiveby nature; naturally; by birth; innately; congenitally
   ヘレンは生来せいらい楽天家らくてんかだ。↗

   Helen is by nature an optimist.
2. adverbsince birth; in one's (entire) life

• Synonym天性てんせいNeutralInnate nature or talent, usually with a positive nuance, as in 「天性の明るさ」; 「生来」 simply says someone is that way from birth.
• Synonym持ち前もちまえNeutralInborn traits used in both speech and writing, as in 「持ち前の明るさ」; it usually points to strengths, while 「生来」 covers good and bad alike.
• Related性格せいかくNeutralThe most general word for character or personality; also covers the traits of things. It says nothing about whether the trait is inborn.
• Related質しつNeutralQuality or calibre, as in 「質がいい」; mostly about things, and does not imply anything inborn.
• Related性質せいしつNeutralNature or disposition, said of both people and things; it does not stress that the trait is inborn.
• Related気質きしつNeutralRead 「きしつ」, it means temperament; in psychology it specifically denotes innate emotional response tendencies. 「生来」 also works as an adverb for 'born that way'.
• Related素質そしつNeutralInborn qualities seen as potential for future development, as in 「音楽の素質」.
• Related根性こんじょうNeutralColloquial: grit and determination, but also a base, stubborn streak, as in 「根性がある」; it does not stress being inborn.
• Related気性きしょうNeutralTemper or disposition, often describing how intense or fiery it is, as in 「気性が荒い」.
• Related本性ほんしょうNeutralOne's true nature, often with a negative nuance, as in 「本性を現す」.
• Related真性しんせいWrittenWritten style: genuine, original nature; also used in medical terminology as 「真性」.
• Related天資てんしWrittenWritten style: natural endowment or aptitude; rare. Leans toward talent and ability, and unlike 「生来」 it is not used as an adverb.
• Related天質てんしつWrittenWritten style: inborn talent; very rare and close in sense to 「天資」.
• Related禀性ひんせいWrittenWritten style: inborn temperament or disposition; rare. Identical in sound and meaning to 「稟性」.
• Related賦性ふせいWrittenWritten style: innate nature; very rare and rather archaic. Not used as an adverb, unlike 「生来」.
• Related資性しせいWrittenWritten style: natural disposition, talent and aptitude; rare. 「生来」 focuses on simply being that way from birth.
• Related稟性ひんせいWrittenWritten style: inborn nature; 「稟」 carries the sense of receiving. Rare, and not used as an adverb.
• Related気立てきだてNeutralTemperament or kind-hearted nature, often praising someone's character, as in 「気立てがいい」; it does not stress being inborn.
• Antonym後天的こうてんてきWrittenWritten style: acquired after birth — the direct opposite of 「生来」's sense of being that way from birth.

For character in general, say 「性格」. In written or formal prose, 'that way from birth' is 「生来」, as in 「生来の怠け者」 or 「生来体が弱い」. Innate talent is 「天性」; inborn strengths are 「持ち前」; acquired traits are 「後天的」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 生うまれつき。また、生うまれつきもって生うまれた性質せいしつや性格せいかく。
2. 生うまれつき。うまれたときから。