As ISKCON's Governing Body Commission (GBC) clarified recently while appointing female dīkṣā gurus, they rely on the teachings of Swami Prabhupada and Chaitanya Mahaprabhu and not that of Ramanujacharya:
The primary bases for this decision are the expressed desires and instructions on guru qualifications of ISKCON's Founder-acarya His Divine Grace Srila ...
Prof Mookerji in his "Ancient Indian Education (Brahmanical and Buddhist)" Page 51 says
Women were then admitted to full religions rites and consequently to
complete educational facilities. The wife was a regular participator
in the sacrificial offerings of the husband [Rv. i, 122,2; 131,3; iii,
53, 4-6; v, 43,15; viii, 31,5; x, 86,10; etc.]. ...
A twice-born person, without having the Upanayana within the prescribed time, is called a Vratya in the scriptures. He is treated like an uninitiated person (a Shudra) although he might be a Brahmin by birth.
There are some remedies available for him (like the Vratyastoma Yajna) performing which he can regain his status of a twice-born.
71 For a Brahmin the ...
You can not ask for scientific reasons here as it will be considered as off-topic. But you can ask for significance or just reasons behind some practice.
The waist band is prescribed in the scriptures in the dress code. It is called the "Kati Sutra". Without wearing this Kati Sutra one is not qualified to perform Srauta and Smarta rituals. That is why you'...
After Brahmopadesham or Upanayana one becomes a Dvija and he is then eligible to recite Vedas, perform Sandhya, perform certain Vedic rituals and Vratas.
Manu Smriti 2.171. They call the teacher (the pupil’s) father because
he gives the Veda; for nobody can perform a (sacred) rite before the
investiture with the girdle of Munga grass.
2.172. (He ...
Can someone do Upanayan ritual later in life say post 25 years of age?
Yes, but you have to do prayaschitta before that.
It is true that after the age limit, one cannot normally do Upanayana.
For the Brāhmaṇa the Sāvitrī does not lapse till the sixteenth year; for the Kṣatriya till the twenty-second year; and for the Vaiśya till the twenty-...
Parashara Smriti is missing the Achara Kanda, that any Smriti must have. So, it does not say anything regarding the details of how the Upanayana ceremony should be performed. But it does talk about the sacred thread which is invested during the Upanayana ceremony.
If, while performing the rite of Achamana, he has his Lead or throat wrapped with cloth, or ...
Chandogya Upanishad VIII.15.1 says (Swami Gambhirananda translator):
Brahma imparted this knowledge that was such to Prajpati, Prajpati (imparted it) to Manu, (and) Manu to the creatures. Having studied the Vedas in the teacher's house in accordance with the injunctions, during leisure after performing the duties to the teacher, he returns home from the ...
What you saw is probably a modern form of the mekhalā (girdle) which is tied to boys during upanayana (initiation). The Manusmṛti says the tying of the girdle is done as part of a saṃskāra called Mauñjībandhana:
baijikaṃ gārbhikaṃ cainaṃ dvijānāmapamṛjyate || 2.27 ||
Of twice-born men the ...